<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>

    <style>
        div {
            color: white;
            width: 300px;
            height: 300px;
        }

        div:nth-child(odd) {
            background-color: #0000FF;
        }

        div:nth-child(even) {
            background-color: rgba(255, 0, 0, 0.7);
        }

        div.small-div {
            width: 200px;
            height: 200px;
        }

        div#big-div {
            width: 400px;
            height: 400px;
        }

        div.hover-div:hover {
            background-color: orange;
        }
    </style>
</head>

<body>
    <div class="small-div">1</div>
    <div id="big-div">2</div>
    <div>3</div>
    <div class="small-div">4</div>
    <div class="small-div hover-div">5</div>
    <div>6</div>
    <div>7</div>
    <div class="hover-div">8</div>
    <div>9</div>
    <div>10</div>
</body>

</html>